Which program allows you to modify existing partition sizes, enabling you to shrink or grow partitions on a drive?

The correct choice is a program called "parted," which is designed specifically for managing disk partitions. Parted provides a user-friendly interface that allows users to resize, create, delete, and manipulate partitions on a storage device. One of its key features is the ability to shrink and grow partitions, accommodating changes in storage needs effectively.

Parted supports various file systems and is capable of handling both MBR (Master Boot Record) and GPT (GUID Partition Table) partitioning schemes, making it a versatile tool for both modern and traditional systems. This capability is particularly useful in scenarios where space needs to be reallocated among different partitions, such as enlarging a root partition while reducing the size of a separate data partition.

While programs like gdisk, fdisk, and cfdisk are also related to partition management, they do not offer the same level of flexibility when it comes to resizing existing partitions. Gdisk focuses on GPT partition tables, while fdisk and cfdisk are more limited in functionality and primarily used for creating, deleting, or listing partitions without resizing capabilities. Therefore, in the context of modifying partition sizes, parted stands out as the appropriate choice.